Many mobile devices undergo functional testing after manufacturing. One such test is an AC charging test, also referred to as a fast charging test. The AC charging test applies DC current that is converted from AC current to AC charge contacts of a mobile device to test the mobile device's circuits associated with charging a battery installed in the device.
During an AC charging test, the battery of a mobile phone is removed, the mobile phone is typically mounted in a battery emulator which is connected in place of the battery. The battery emulator is in turn mounted on a test fixture. To test AC charging, an AC charge is applied through the text fixture and/or battery emulator to the AC charging contacts on the mobile phone. The battery emulator is used to assess whether application of the AC charge would have resulted in an effective charge of a battery, if one had been present. The battery emulator and test fixture can be used for other tests, such as calling and receiving testing, speaker and microphone testing, light sensor and LED testing, camera and flasher testing, keyboard brightness testing, etc. to name a few specific examples.
To test AC charging on mobile devices with AC charge contacts located at the back of the phone, two brass balls can be used to apply the test AC charge to the AC charge contacts. These brass balls are located on the battery emulator.